How many Zikas will it take?

Gradually the Public Health gaze is turning towards the minor acute events that trigger serious long term illnesses and chronic conditions. “About time too”, say many campaigners.

For social scientists, it is very interesting to observe major changes in medical thinking and practice. As we try and analyse the context in which they take place, we find fascination in the relationships (and sometimes conflicts) between the social forces and the various agents involved. Right now, a major shift is beginning to occur in European and American Public Health. The ‘public health gaze’ is starting to widen out from its narrow 40 year focus on ‘personal lifestyle’ and beginning to take seriously the idea that some of our most intractable long-term problems are rooted in ‘good old-fashioned’ infection.

The development and spread of the Zika virus has caught the attention of the world and is the latest example of the threat posed by an initially mild infection which can have the dramatic long-term effects on wellbeing. One of the striking aspects of Zika is, of course, that like Rubella before it, the principal long term effect is not on the original patient, but on subsequently born children. It is this aspect of the Zika crisis that has grabbed the headlines in the USA and Europe and, all too often, press reports have given the impression that this virus is something conceptually new and particularly frightening.

But in a wider sense, the Zika virus should be seen as a member of a much larger family of infections that, even though in many cases they are barely noticed by the sufferer at the time, go on to cause long term, serious and debilitating disease at a later date. For decades, in the developed industrial world, these illnesses tended to be seen as exotic and mainly of interest to a medical minority (see, for example, Bannister’s visionary 1988 paper). In recent years, though the magnitude of the problem of chronic illness triggered by simple infection has slowly been moving into the Public Health mainstream.

The infectious causes of later chronic disease have been known about for decades and centuries. In South America, long before Zika hove into view, Chagas’ disease (where a person becomes infected with a single-celled insect-borne parasite) was a major cause of serious and fatal heart problems in people 10 to 30 years after they were bitten by the carrying insect. Some researchers think Charles Darwin caught Chagas’ while carrying out shore-based research from the Beagle, explaining his ‘broken health’ in later life. Even after decades of infrastructural improvement in Argentina, Chile, Bolivia, Brazil and Paraguay (the culprit bugs are often found in the thatched roofs of poor people’s houses), recent estimates are that there remain over 7 million people with Chagas’ infection, of whom 30% to 40% will go on to develop serious heart problems. In earlier decades the numbers were much larger, causing many deaths and placing a significant burden on healthcare systems.

In North America and Northern Europe, a similar scenario is being played out with Lyme Disease, an infection carried by ticks which mainly feed on animals but are not averse to taking blood from passing humans. Lyme is known to cause a range of very long lasting inflammatory conditions and severe fatigue in an as yet unknown number of sufferers. The problems attendant on Lyme can not only last for many years, they are usually at their most devastating many years after the original tick bite (which was often not even noticed by the victim).

While Zika, Chagas’ and Lyme are all zoonotic diseases, some of the more striking members of the ‘serious-illness-years-after-minor-infection’ family are more common microbes which pass readily from human to human, such as the relatively well known Human Papilloma Virus . And it is one of these common person-to-person infections (Adenovirus 36) that is currently making particular waves in the Public Health world. This is because it has the potential to trigger obesity in the years following an infection, at least in a percentage of cases. Again, as is so common in this story, the original infection is normally easily shrugged off (or not even noticed) by the person catching it.

If obesity – the number one crisis in Western medicine – has viral origins in a significant number of cases, the implications for Public Health and Health Promotion are huge. Apart from anything else, it might reveal that the decades long campaign to get people to eschew fats and eat lots of carbohydrates has been worse than a waste of time. For those suffering from some kind of post-viral metabolic syndrome, following the advice to “base your meals on starchy foods” will have been a sure route to a big waist line and the risk of diabetes etc etc. All of which could have been avoided by a quick antibody test. It would be fair to say that Nutritionists and Health Promotion people haven’t traditionally thought of themselves as potential causes for mass iatrogenic disease – but it seems that those times might be changing.

One particularly 21st century set of social actors involved in the debates and movements that are shaking up the chronic condition world are patient activists and pressure groups. Public voices and grass-roots campaigns (with the internet as their weapon of choice) are busy trying to shape the agenda and pressurise decision makers. An important dimension in the struggles of these patient groups is their feeling that the medical establishment has never taken the infectious roots of long-term illness seriously. This is something of a new element in the Public Health equation and, as you might imagine, two prime examples are to be found in the worlds of Lyme Disease and Obesity.